Fan

ABSTRACT

A fan includes a frame and an impeller. The frame defines a hole in a middle of the frame. An inner wall of the frame bounding the hole defines a circumferential groove and forms a circumferential protrusion adjoining the groove. The impeller is received in the hole of the frame. When the impeller is rotated, airflow through the hole is pressurized by the groove and the protrusion, and concentrates when the airflow is blown out of the hole.

BACKGROUND

1. Technical Field

The present disclosure relates to a fan.

2. Description of Related Art

FIG. 1 shows a typical fan 80 comprising a frame 81 and an impeller 83.A circular hole 85 is defined in a middle of the frame 81, for receivingthe impeller 83. An inner surface of the frame 81 bounding the hole 85is smooth. When the impeller 83 is rotated, air is drawn into the hole85 from a side of the fan 80, and a considerable amount of air isradially flown out of the hole 85 from an opposite side of the fan 80.Thereby, the fan 80 may not effectively dissipate heat for some deviceswhich need heat dissipation by more concentrated air.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present embodiments can be better understood withreference to the following drawings. The components in the drawings arenot necessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the present embodiments.Moreover, in the drawings, all the views are schematic, and likereference numerals designate corresponding parts throughout the severalviews.

FIG. 1 is a plan, sketch view of a conventional fan in use.

FIG. 2 is an assembled, isometric view of an embodiment of a fan.

FIG. 3 is a plan, sketch view of the fan of FIG. 2 in use.

DETAILED DESCRIPTION

The disclosure, including the accompanying drawings, is illustrated byway of example and not by way of limitation. It should be noted thatreferences to “an” or “one” embodiment in this disclosure are notnecessarily to the same embodiment, and such references can mean “atleast one.”

FIGS. 2 and 3 show an exemplary embodiment of a fan 10 comprising aframe 12 and an impeller 14.

The frame 12 comprises two opposite sidewalls 121. A hole 123 having anelliptic cross section is defined in a middle of the frame 12, extendingthrough the sidewalls 121. The impeller 14 is mounted in the hole 123. Aplurality of circumferential grooves 125 is defined in an inner wall 124of the frame 12 bounding the hole 123, such that two circumferentialprotrusions 126 are formed on the inner wall 124 adjoining oppositesides of each groove 125. In the embodiment, a cross section of eachgroove 125 and each protrusion 126 is arc-shaped, such that the grooves125 and the protrusions 126 cooperate to form a wave-shaped surface onthe inner wall 124 of the frame 12.

In use, the impeller 14 is rotated, airflow is drawn into the hole 123from an end of the hole 123, and is blown out of the hole 123 from anopposite end of the hole 123. Because the spaced grooves 125 andprotrusions 126 are formed on the inner wall 124 bounding the hole 123,the airflow through the hole 123 is pressurized by the grooves 125 andthe protrusions 126, and concentrates when the airflow is blown out ofthe hole 123. Thereby, the fan 10 can provide stronger, concentratedairflow.

In the embodiment, a cross section of the hole 123 is elliptic, whichcan reduce wind noise.

In other embodiments, the inner wall 124 can define only onecircumferential groove 125 and form only one circumferential protrusion126 adjoining the groove 125.

Even though numerous characteristics and advantages of the embodimentshave been set forth in the foregoing description, together with detailsof the structure and the functions of the embodiments, the disclosure isillustrative only, and changes may be made in details, especially in thematters of shape, size, and arrangement of parts within the principlesof the embodiments to the full extent indicated by the broad generalmeaning of the terms in which the appended claims are expressed.

What is claimed is:
 1. A fan, comprising: a frame defining a hole in amiddle of the frame, an inner wall of the frame bounding the holedefining a circumferential groove and forming a circumferentialprotrusion adjoining the groove; and an impeller received in the hole ofthe frame, wherein when the impeller is rotated, airflow through thehole is pressurized by the groove and the protrusion, and concentrateswhen the airflow is blown out of the hole.
 2. The fan of claim 1,wherein the groove and the protrusion cooperate to form a wave-shapedsurface on the inner wall of the frame.
 3. The fan of claim 2, wherein across section of each of the groove and the protrusion is arc-shaped. 4.The fan of claim 1, wherein a cross section of the hole is elliptic. 5.A fan, comprising: a frame defining a hole in a middle of the frame, aninner wall of the frame bounding the hole defining a plurality ofcircumferential grooves and forming two circumferential protrusionsadjoining opposite sides of each groove; and an impeller received in thehole of the frame, wherein when the impeller is rotated, airflow throughthe hole is pressurized by the plurality of grooves and protrusions, andconcentrates when the airflow is blown out of the hole.
 6. The fan ofclaim 5, wherein the plurality of grooves and protrusions cooperate toform a wave-shaped surface on the inner wall of the frame.
 7. The fan ofclaim 6, wherein a cross section of each groove and each protrusion isarc-shaped.
 8. The fan of claim 5, wherein a cross section of the holeis elliptic.